Multichannel transducer with glass support elements

ABSTRACT

A multichannel magnetic transducer assemblage which includes a ferrite block member notched along one edge thereof to provide a series of ramp like slots extending from one face thereof to an adjacent face thereof. The area between the slots forming a series of teeth over which separate C-shaped ferrite slabs are placed to form with the mating teeth a series of active transducer gaps.

United States Patent 1191 Best et al. Jan. 7, 1975 [54] MULTICHANNEL TRANSDUCER WITH 3,418,434 12/1968 Groenewegen 340/l74.l E GLASS SUPPORT ELEMENTS Solyst (II: Inventors: gz '1!- Pi egg aye tf l l t h f 3:813:693 5/1974 Gooch et al. 360/119 omas l prmg 1e 0t 0 P E B r d K k I rzmary xammere nar omc Asslgneer p y Rand Corporation, Blue Bell, Assistant Examiner-Robert s. Tupper Attorney, Agent, or Firm-Charles C. English [22] Filed: June 18, 1973 1 1 pp 371,077 57 ABSTRACT A multichannel magnetic transducer assemblage which includes a ferrite'block member notched along [58] Fie'ld 179/100 100 2 one edge thereof to provide a series of ramp like slots 340/174 1 346/74 M 1 extending from one face thereof to an adjacent face 127 thereof. The area between the slots forming a series of teeth over which separate C-shaped ferrite slabs are placed to form with the mating teeth a series of active [56] References Cited transducer gain 1 UNITED STATES PATENTS 3,151,796 10/1964 Lipschutz 340/174.1 E 3 Claims, 4 Drawing Figures 20e a. i I1. 1

I I1 I.

I ll "1 MULTICHANNEL TRANSDUCER WITH GLASS SUPPORT ELEMENTS BACKGROUND OF THE INVENTION This invention relates to a multichannel magnetic transducer and to a method of fabricating the same.

The magnetic transducer of the present invention is particularly suited for use with magnetic discs, drums or tape units commonly employed with digital computers. In its preferred embodiment the present invention contemplates a ferrite type of transducer. Such transducers are not new per se, but the present transducer has the advantages of being simple and inexpensive to make; has a very low loss characteristic and provides a good production yield.

SUMMARY OF INVENTION In accordance with the teaching of the present invention, a multichannel transducer is provided which comprises a first comparatively thick rectangular ferrite block machined to form a common I piece for the multichannel transducer assemblage. The block has a top face and a front face extending at right angles to one another and bounded by a common edge. A series of spaced ramp like slots are cut downwardly from the top face of the block to its front face across the common edge. The slots form a series of intermediate tooth portions which act as the individual I pole pieces for the respective transducer channels. Bonded to the top face of the first ferrite block is a mating second ferrite block which has a C-shaped cross section. The second block is cut on each side of a tooth along lines that parallel the slots to thus form a separate C-shaped slab overlying each tooth of the first block. Each of the C-shaped slabs and its mating tooth portion form an active transducer gap along the common edge of the first block. The separate C-shaped slabs are made much wider than the teeth of the I block to thus provide a large area, low loss back gap for the transducer and at the same time permit a good bonding surface between the C-shaped slab and the I piece. Likewise, the tooth portions formed by the ramp like slots are made shallow so that the remaining surfaces act as a protective support for the teeth.

An object of the present invention is to provide a multichannel transducer which is simple in design and inexpensive to fabricate.

It is another object of the invention to provide a multichannel transducer which has low loss characteristics.

It is still another object of the present invention to provide a multichannel transducer which offers a high production yield.

These and other objects of the present invention will become apparent from the following description when read in connection with the drawings, in which:

FIG. 1 is a perspective view of the I block employed by the present invention;

FIG. 2 is a perspective view of a fragmentary portion of the C piece employed by the present invention;

FIG. 3 is a perspective view showing the C and 1 pieces of FIGS. 1 and 2 bonded together; and

FIG. 4 is a perspective view showing a fragment of the completed multichannel transducer.

DESCRIPTION Reference will now be made to the drawings as the description of the invention proceeds. In accordance with the teaching of the present invention, the multichannel magnetic transducer described herein comprises a unitary I piece shown at 10 in the figures. The I piece 10 is made from any suitable ferrite material which has been cut to the desired length L, width W and thickness T dimensions. In a typical embodiment where a 15 channel transducer was fabricated, the finished length L was made equal to 1.204 inches, the thickness T to 0.3 inches and the width W to 0.280 inches. After the block 10 has been machined to its de' sired dimensions, a series of uniformly spaced slots 11 through 14 are cut on an angle, from the top face 10a of the block 10 to its front face 10b. In the typical embodiment this angle was 15 to 20. The slots 11 through 14 form a series of spaced teeth members 15 through 19. Again, in the typical embodiment each slot was 0.064 inches wide and each tooth 15 through 19 was 0.008 inches wide. The height of the teeth 15 through 19 at the active typical embodiment were made equal to 0.025 inches. Each of the teeth 15 through 19 form the individual I pole piece for the respective channels of the transducer. Forming the pole pieces 15 to 19 as described offers the advantages that the pole pieces are both supported and protected by the surrounding material so that they are not readily broken during fabrication and assembly of the transducer. The slots 11 to 14 are then filled with a melted glass, as illustrated at 12 and 14 (FIG. 3). The surface 10a is then lapped to remove the excess glass and to restore it to the desired degree of flatness, typically one light band or better. A suitable spacer material such as platinum or silicon monoxide may then be deposited on the end tooth portions 15 and 19 as shown at 15a. The spacer material establishes the size of the active gap of the transducer elements.

After the I piece 10 has been prepared as described,

a unitary C member is prepared. TheC member shown sions corresponding to the length and width dimensions of the I piece 10. The longitudinal channel 21 in the typical embodiment was cut to a depth of0.045 inches and to a-width of 0.220 inches leaving surfaces 20a and 20b of 0.050 inches and 0.010 inches, respectively in width. These latter surfaces are lapped to the desired degree of flatness which again may be one light band or better, and the C member 20 is then bonded along the surfaces 20a and 20b to the mating surface 10a of the transducer as shown in FIG. 3. In the bonding operation a glass bond utilizing conventionally known glass bonding techniques can be employed and the glass can if desired have a lower temperature than that used to fill the slots 11 to 14.

After the C member has been bonded to the I member the active gap end 10b of the assembly is machined to produce the proper gap height 11 (FIG. 2). Also at this time a series of air spoilers as shown by grooves 22 and 23 may be machined into the I member as shown in FIG. 4. These air spoilers are grooves cut to a depth of for example 0.015 inches and to a width of 0.047 inches, centered about the slots 11 to 15 cut in the 1 piece 10. The purpose of the spoilers 22 and 23 is to provide a vent area for air trapped between the recording medium not shown) and the face 10b of the transducer as the medium moves across the transducer face.

These grooves then provide a pressure relief for the entrained air so that the recording medium can be moved in close proximity to the active face b of the transducer.

Finally, after the active surface 10b has been machined to establish the desired gap height, the active face of the assembled transducer then can undergo a final lapping operation.

The final step in the fabrication of the multichannel transducer is the formation of the individual C members c, 20d, 202 etc. as shown in FIG. 4. These members are formed by transversely cutting the common C member midway between each of the notches 11 through 14 so as to provide a relatively wide C piece for each channel of the transducer. In a typical embodiment the C pieces were 0.040 inches wide. The C members being relatively wide provide a large surface (0.040 X 0.050 inches) at their back gap (along surface 20a). This large surface at the back gap provides both a good mechanical bond to the I member 10 and a large area across which the electrical losses in the transducer itself can be kept to a minimum. After the individual C pieces 20c, 20d, 202 etc. have been formed, suitable signal windings such as shown at 24 and 25 in FIG. 4 are wound around each of the C pieces as illustrated.

The resulting head structure can then be contoured and mounted directly in a suspension system. In the alternative, additional case work such as a slider block can be employed in the head mounting but is not required depending upon the application of the head. Also if desired the head can be initially fabricated with 11 channels and then sliced to provide an assembly having any number of channels m where m is less than n.

What is claimed is:

l. A multichannel magnetic transducer assemblage comprising: a unitary I piece which includes a ferrite block member having top, front, bottom and rear faces wherein the intersection between the front and top faces forms a front edge for the top face of the block and the intersection between the top and rear faces forms a rear edge for the top face of the block, a series of uniformily spaced ramp-like slots extending downwardly from a line intermediate said front and rear edges of the top face of said block to a line intermediate the front edge of said block and the bottom face of said block, said series of slots forming a series of teeth along the front edge of said block, a series of spaced C shaped ferrite slabs bonded to the top face of said block, each of said slabs overlying a respective tooth of said series of teeth to form with said teeth a series of active transducer gaps spaced along the front edge of said block and a corresponding series of back gaps spaced along the rear edge of said block, and a melted glass material filling each of said slots to provide structural support for said teeth and the overlying C-shaped ferrite slabs.

2. The transducer assemblage of claim 1 wherein each of said ferrite slabs is wider than its mating tooth.

3. The structure of claim 1 wherein a plurality of air spoiling grooves are formed in the front face of the block extending from the bottom edge of the block toward the top face thereof between said teeth. 

1. A multichannel magnetic transducer assemblage comprising: a unitary I piece which includes a ferrite block member having top, front, bottom and rear faces wherein the intersection between the front and top faces forms a front edge for the top face of the block and the intersection between the top and rear faces forms a rear edge for the top face of the block, a series of uniformily spaced ramp-like slots extending downwardly from a line intermediate said front and rear edges of the top face of said block to a line intermediate the front edge of said block and the bottom face of said block, said series of slots forming a series of teeth along the front edge of said block, a series of spaced C-shaped ferrite slabs bonded to the top face of said block, each of said slabs overlying a respective tooth of said series of teeth to form with said teeth a series of active transducer gaps spaced along the front edge of said block and a corresponding series of back gaps spaced along the rear edge of said block, and a melted glass material filling each of said slots to provide structural support for said teeth and the overlying C-shaped ferrite slabs.
 2. The transducer assemblage of claim 1 wherein each of said ferrite slabs is wider than its mating tooth.
 3. The structure of claim 1 wherein a plurality of air spoiling grooves are formed in the front face of the block extending from the bottom edge of the block toward the top face thereof between said teeth. 